Diesel fuel system with advanced priming

ABSTRACT

This invention relates to an aerating device for a fuel system, and in particular, to an aerating device for a fuel system supplying fuel to an engine from a fuel tank. The invention includes, for example, a solenoid valve accessing a flow path to the fuel tank, and a control unit opening a closing the solenoid valve, such that opening of the solenoid valve permits fuel and air to flow back through the flow path to the fuel tank and naturally separate.

TECHNICAL FIELD

This invention relates generally to an aerating device for a fuelsystem, and in particular, to an aerating device for a fuel systemsupplying fuel to an engine from a fuel tank.

BACKGROUND OF THE INVENTION

In many existing engine applications it is difficult to rapidly prime(eliminate air from) the fuel system, especially after fuel systemmaintenance, such as a fuel filter change. This is often due to theinherently high restriction of mechanically driven pumps when the engineis not running. Fixed orifices are used to provide a flow path aroundthe restrictive component. However, since these orifices tend to besmall or have check valves to prevent leakage through the system, theorifices can waste power in normal engine operation, and still notreduce the restriction enough for efficient priming. Other alternativesinclude manually opening the fuel system by loosening a fitting oropening a bleed screw to allow aerated fuel to escape. However, thismethod is both messy and labor intensive.

FIG. 1 is a schematic diagram of a fuel priming system used in theconventional art. Such a fuel priming system 1 may include, for example,a fuel tank 2 in which fuel is pumped to an engine through the fuel rail9 to injectors. The fuel passes through a pre-filter 3 to a priming pump4 which compresses air pockets in the system during the prime cycle.Fuel then passes to a secondary fuel filter 5, and onward to highpressure pump assembly 6. High pressure pump assembly 6 includes checkvalves and bleed orifices 7 that allow air pressure in the system to bevented. However, such valves and orifices require the system to generateenough air pressure to open the valves and result in internal leakage inthe system, even if a low pressure drain line 8 is fed back to the fueltank 2.

U.S. Pat. No. 7,431,021 discloses a fuel vapor separator in a fueldelivery system of a marine engine. With reference to FIG. 2, engine 12draws liquid fuel from a fuel tank 20. A low pressure fuel supply pump26 or lift pump typically pulls fuel from the tank 20 through a supplyline 24. The fuel is delivered to a vapor separator 28, which collectsand discharges vapors given off due to incoming low fuel pressure,normal vaporization of fuel, etc. High pressure pump 30 may be connectedto the vapor separator 28 and pumps the fuel under pressure to thecylinders of the engine, such as through a fuel injector system 32.Unused fuel is returned to the vapor separator 28 via return line 34.The vapor separator 28 includes a vent device 36 to vent fuel vaporsthrough the air intake of the engine.

SUMMARY OF THE INVENTION

This invention relates to an aerating device for a fuel system, and inparticular, to an aerating device for a fuel system supplying fuel to anengine from a fuel tank. The invention includes, for example, a solenoidvalve accessing a flow path to the fuel tank, and a control unit openinga closing the solenoid valve, such that opening of the solenoid valvepermits fuel and air to flow back through the flow path to the fuel tankand naturally separate.

In one embodiment, there is an aerating device for a fuel systemsupplying fuel to an engine from a fuel tank, including a flow pathcoupled to the fuel tank allowing fuel and air to separate; a valveaccessing the flow path to the fuel tank; and a control unit controllingthe valve, such that opening of the valve permits fuel and air to flowback through the flow path to the fuel tank for separation.

In one aspect, the device further includes a fuel filter receiving fuelfrom a fuel tank via a priming pump; and a high pressure pump assemblyto provide fuel to a fuel rail of the engine, wherein the valve islocated between the fuel filter and the high pressure pump assembly withthe flow path coupled between the valve and the fuel tank.

In another aspect, the control unit is one of a switch, control moduleand engine control computer.

In yet another aspect, the valve is one of a solenoid valve andspool-type valve.

In still another aspect, the spool-type valve comprises a housing, amovable spool and a spring with an integrally-molded disc such thathydraulic pressure in the housing causes the spool to move, therebyallowing air in the fuel system to aerate.

In another aspect, the engine is a diesel engine.

In another embodiment, there is an aerating device for a fuel systemsupplying fuel to an engine from a fuel tank, including a fuel sensor todetect a ratio of fuel to air; a valve to aerate the fuel system; and acontrol unit controlling the valve based on the detected ratio from thefuel sensor, wherein controlling the valve to open enables the system tobe primed.

In still another embodiment, there is a method of aerating a fuel systemsupplying fuel to an engine from a fuel tank, including accessing a flowpath using a valve, the flow path coupled to the fuel tank; controllingthe valve such that opening of the valve permits fuel and air to flowback to the fuel tank; and separating air and fuel in the fuel tank.

These and other features and advantages of this invention will becomemore apparent to those skilled in the art from the detailed descriptionof a preferred embodiment. The drawings that accompany the detaileddescription are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a fuel priming system in accordancewith the prior art.

FIG. 2 is a schematic diagram of a fuel delivery system in accordancewith the prior art.

FIG. 3 is a schematic diagram of a fuel priming system with a solenoidvalve in accordance with one embodiment of the invention.

FIG. 4 is a schematic diagram of a fuel priming system with a solenoidvalve and fuel sensor in accordance with one embodiment of theinvention.

FIG. 5 is an enlarged diagram of the automatic priming system inaccordance with one embodiment of the invention.

FIG. 6 is a schematic diagram of a fuel priming system with a spool-typevalve in accordance with one embodiment of the invention.

FIG. 7 is an enlarged diagram of an exemplary spool-type valve for usein accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The invention incorporates a low restriction flow path back to the fueltank where fuel and air can separate naturally. The flow path isincorporated into the existing circuit before the point of highrestriction. This flow path can be opened and closed, in one embodiment,by a solenoid valve producing an efficient priming system with less messand labor. In another embodiment, the added flow path can be opened andclosed by a spool-type valve when an electric priming pump is energized.A fuel sensor may be used to detect when fuel is present in the system.If no fuel is detected, the system assumes air is in the system andvents the air using the flow path. An additional advantage is that thepower-wasting fixed orifice is no longer needed to assist with priming.FIG. 3 is a schematic diagram of a fuel priming system with a solenoidvalve in accordance with one embodiment of the invention. Such a fuelpriming system 41 may include, for example, a fuel tank 42 in which fuelis pumped to an engine through the fuel rail 49 to injectors. The fuelpasses through a pre-filter 43 to a priming pump 44 which compresses airpockets in the system during the prime cycle. Fuel then passes to asecondary fuel filter 45, and ultimately to high pressure pump assembly46. Unlike the conventional system described with respect to FIG. 1,this embodiment of the invention includes a valve (for example, asolenoid valve or spool-type valve 47) placed in the system just priorto the high pressure pump assembly 46. In this embodiment, solenoidvalve 47 accesses a low restriction flow path 48 back to the fuel tankwhere fuel and air can naturally separate. The flow path 48 is openedand closed by the solenoid valve producing an efficient priming systemwith less mess and labor. The solenoid valve 47 can be controlledmanually with a switch, automatically with control module 47A orconnected to the existing engine/chassis control computer (i.e. thecontrol module can be controlled by ECM or a separate control module).

In an alternative embodiment, the fuel priming system utilizes a fuelsensor 45A to detect whether fuel or air is present in the system. Thefuel sensor 45A may be included in the filter (as shown), or provided asa stand alone assembly (not shown). FIG. 4 is a schematic diagram of afuel priming system with a solenoid valve and fuel sensor in accordancewith one embodiment of the invention. The fuel priming system 41 issimilar to the system in FIG. 3, but does not require a return path backto the fuel tank. Rather, the embodiment of FIG. 4 uses the fuel sensor45A to detect a ratio of fuel to air in the filter. Based on thedetection, the system is automatically primed by opening and closing thesolenoid valve 47. FIG. 5 is an enlarged diagram of the automaticpriming system in accordance with one embodiment of the invention. Asillustrated, fuel filter 45 includes a fuel sensor 45A to detect fuel inthe filter. If fuel sensor 45A detects fuel in fuel filter 45, thesystem is primed and the solenoid valve 47 is kept closed, and thepriming pump 44 is shut off. If, on the other hand, the fuel sensor 45Adetects air in the system (in one embodiment, if fuel is not detected,air is deemed present), solenoid valve 47 is opened and priming pump 44is turned on such that air may be purged through the system, viasolenoid valve 47. When the fuel sensor 45A detects the presence of fuelin the fuel filter 45, solenoid valve 47 is closed and the priming pump44 is turned off. Significantly, this results in a reduction of primingtime as much as 80% compared to the conventional techniques.

FIG. 6 is a schematic diagram of a fuel priming system with a spool-typevalve in accordance with one embodiment of the invention. Such a fuelpriming system 51 may include, for example, a fuel tank 52 in which fuelis pumped to an engine through the fuel rail 59 to injectors. The fuelpasses through a pre-filter 53 to a priming pump 54 which compresses airpockets in the system during the prime cycle. Fuel then passes to asecondary fuel filter 55, and ultimately to high pressure pump assembly56. Unlike the conventional system described with respect to FIG. 1,this embodiment of the invention includes a spool-type valve 57(described below) placed in the system just prior to the high pressurepump assembly 56. Spool-type valve 57 accesses a low restriction flowpath 58 back to the fuel tank where fuel and air can naturally separate.The flow path 58 is opened and closed by the spool-type valve producingan efficient priming system with less mess and labor. The spool-typevalve is automatically actuated by fuel pressure when an the primingpump is energized. When the priming pump is de-energized, a spring inthe valve returns the spool-type valve to it's original position,thereby closing off the additional flow path.

FIG. 7 is an enlarged diagram of an exemplary spool-type valve for usein accordance with one embodiment of the invention. Operation of aspool-type valve is disclosed below with reference to the Figure. Thespool-type valve 57 includes, for example, a movable spool or poppet S1with an integrally-molded rubber disc MR1, a spring S2 and housing H1.In the closed (or “at rest”) position, the spring S2 holds the spool 57to the right such that it does not allow hydraulic communication (flow)between ports P3 and P2. As the hydraulic pressure of port P1 increases,a force imbalance builds up and eventually causes the spool 57 to shiftto the left (open), which then allows hydraulic communication (flow)between ports P3 and P2. This occurs since the hydraulic pressure of P1acts on surface area A1, which is larger than area A2. The design can bemade to be relatively insensitive to the magnitude of the hydraulicpressure at P2 with proper selection of the sealing areas. It should benoted that the spool 57 is shown with a series of drillings whichcommunicate the fluid pressure of P3 to the back side (spring chamberarea) or the spool S1.

The foregoing invention has been described in accordance with therelevant legal standards, thus the description is exemplary rather thanlimiting in nature. Variations and modifications to the disclosedembodiment may become apparent to those skilled in the art and do comewithin the scope of the invention. Accordingly, the scope of legalprotection afforded this invention can only be determined by studyingthe following claims.

1. An aerating device for a fuel system supplying fuel to an engine froma fuel tank, comprising: a flow path coupled to the fuel tank allowingfuel and air to separate; a valve accessing the flow path to the fueltank; and a control unit controlling the valve, such that opening of thevalve permits fuel and air to flow back through the flow path to thefuel tank for separation.
 2. The aerating device according to claim 1,further comprising: a fuel filter receiving fuel from a fuel tank via apriming pump; and a high pressure pump assembly to provide fuel to afuel rail of the engine, wherein the valve is located between the fuelfilter and the high pressure pump assembly with the flow path coupledbetween the valve and the fuel tank.
 3. The aerating device according toclaim 1, wherein the control unit is one of a switch, control module andengine control computer.
 4. The aerating device according to claim 1,wherein the valve is one of a solenoid valve and spool-type valve. 5.The aerating device according to 4, wherein the spool-type valvecomprises a housing, a movable spool and a spring with anintegrally-molded disc such that hydraulic pressure in the housingcauses the spool to move, thereby allowing air in the fuel system toaerate.
 6. The aerating device according to claim 1, wherein the engineis a diesel engine.
 7. An aerating device for a fuel system supplyingfuel to an engine from a fuel tank, comprising: a fuel sensor to detecta ratio of fuel to air; a valve to aerate the fuel system; and a controlunit controlling the valve based on the detected ratio from the fuelsensor, wherein controlling the valve to open enables the system to beprimed.
 8. The aerating device according to claim 7, further comprising:a fuel filter receiving fuel from a fuel tank via a priming pump; and ahigh pressure pump assembly to provide fuel to a fuel rail of theengine, wherein the valve is located between the fuel filter and thehigh pressure pump assembly, and when the fuel sensor detects fuel inthe fuel filter, the valve remains shut, and when the fuel sensordetects air in the system, the valve is opened thereby allowing air tobe purged from the system.
 9. The aerating device according to claim 8,wherein the control unit is one of a switch, control module and enginecontrol computer.
 10. The aerating device according to claim 8, whereinthe fuel sensor is part of the fuel filter.
 11. The aerating deviceaccording to claim 8, wherein the engine is a diesel engine.
 12. Theaerating device according to claim 7, wherein the valve is one of asolenoid valve and spool-type valve.
 13. A method of aerating a fuelsystem supplying fuel to an engine from a fuel tank, comprising:accessing a flow path using a valve, the flow path coupled to the fueltank; controlling the valve such that opening of the valve permits fueland air to flow back to the fuel tank; and separating air and fuel inthe fuel tank.
 14. The method according to claim 13, further comprising:receiving fuel in a fuel filter from a fuel tank via a priming pump; andproviding fuel using a high pressure pump assembly to a fuel rail of theengine, wherein the valve is located between the fuel filter and thehigh pressure pump assembly with the flow path coupled between the valveand the fuel tank.
 15. The method according to claim 13, wherein thecontrol unit is one of a switch, control module and engine controlcomputer.
 16. The method according to claim 13, wherein the valve is oneof a solenoid valve and spool-type valve.
 17. The method according to16, wherein the spool-type valve comprises a housing, a movable spooland a spring with an integrally-molded disc such that hydraulic pressurein the housing causes the spool to move, thereby allowing air in thefuel system to aerate.
 18. The method according to claim 13, wherein theengine is a diesel engine.